Method and apparatus for providing a dynamically variable resistive load during exercise

ABSTRACT

An apparatus for providing a dynamically variable resistive load during exercise includes a wheel unit, a resistance generator, a torque transfer device, an angle measuring device, and a control unit. The wheel unit rotates in response to exertion of a user-applied force during an exercise stroke. The resistance generator generates a resistive torque for resisting rotation of the wheel unit when the user-applied force is exerted. The torque transfer device transfers a fraction of the resistive torque from the resistance generator to the wheel unit. The angle measuring device detects angular rotation of the wheel unit during each exercise stroke. The control unit, in accordance with the angular rotation of the wheel unit during a current exercise stroke, controls the torque transfer device to adjust the fraction of the resistive torque that is transferred to the wheel unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a load for exercise equipment, moreparticularly to a method and apparatus for providing a dynamicallyvariable resistive load during exercise.

2. Description of the Related Art

A known apparatus for providing a resistive load during exerciseincludes a wheel unit, a resistance generator, an electricallycontrolled torque transfer device, and a control unit. The wheel unit isoperable so as to rotate in response to exertion of a user-applied forceduring an exercise stroke. The resistance generator, such as an electricmotor, is operable so as to generate a resistive torque for resistingrotation of the wheel unit when the user-applied force is exerted. Thetorque transfer device, such as an electromagnetic mechanical particleclutch, couples the resistance generator to the wheel unit, and isoperable so as to transfer a fraction of the resistive torque from theresistance generator to the wheel unit. The control unit is coupled tothe resistance generator so as to control activation of the resistancegenerator and direction of the resistive torque generated by theresistance generator. The control unit is further coupled to the torquetransfer device, and controls operation of the torque transfer device inorder to gradually increase the fraction of the resistive torque that istransferred to the wheel unit with reference to a predetermined loadvariation curve during each exercise stroke.

While the aforesaid known apparatus provides a variable resistive loadduring exercise, it does not take into account the actual physicalcondition of the user during exercise. As a result, when the resistiveload is too heavy, the user is likely to get injured due toover-exertion.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a methodand apparatus for providing a dynamically variable resistive load duringexercise that can overcome the aforesaid drawback of the prior art.

According to one aspect of this invention, there is provided a methodfor providing a dynamically variable resistive load during exercise. Themethod is implemented using an apparatus which includes a wheel unitthat is operable so as to rotate in response to exertion of auser-applied force during an exercise stroke, a resistance generatorthat is operable so as to generate a resistive torque for resistingrotation of the wheel unit when the user-applied force is exerted, andan electrically controlled torque transfer device that couples theresistance generator to the wheel unit and that is operable so as totransfer a fraction of the resistive torque from the resistancegenerator to the wheel unit. The method comprises the steps of:

-   -   a) detecting angular rotation of the wheel unit during each        exercise stroke; and    -   b) in accordance with the detected angular rotation of the wheel        unit during a current exercise stroke, controlling the torque        transfer device to adjust the fraction of the resistive torque        that is transferred to the wheel unit.

According to another aspect of this invention, there is provided anapparatus for providing a dynamically variable resistive load duringexercise. The apparatus comprises a wheel unit, a resistance generator,an electrically controlled torque transfer device, an angle measuringdevice, and a control unit. The wheel unit is operable so as to rotatein response to exertion of a user-applied force during an exercisestroke. The resistance generator is operable so as to generate aresistive torque for resisting rotation of the wheel unit when theuser-applied force is exerted. The torque transfer device couples theresistance generator to the wheel unit, and is operable so as totransfer a fraction of the resistive torque from the resistancegenerator to the wheel unit. The angle measuring device detects angularrotation of the wheel unit during each exercise stroke. The control unitis coupled to the torque transfer device and the angle measuring device.In accordance with the angular rotation of the wheel unit detected bythe angle measuring device during a current exercise stroke, the controlunit controls the torque transfer device to adjust the fraction of theresistive torque that is transferred to the wheel unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiment with reference to the accompanying drawings, of which:

FIG. 1 is a schematic side view of a multi-function exercise machinethat incorporates the preferred embodiment of an apparatus for providinga dynamically variable resistive load according to the presentinvention;

FIG. 2 is a schematic block diagram of the preferred embodiment;

FIG. 3 is a schematic side view of the preferred embodiment;

FIG. 4 is a flowchart to illustrate operation of a control unit of thepreferred embodiment; and

FIG. 5 is a flowchart to illustrate operation of a modified control unitof the preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the preferred embodiment of an apparatus 3 forproviding a dynamically variable resistive load according to the presentinvention is shown to be incorporated in a multi-function exercisemachine 2 that includes a known pull unit 21, a known leg extension unit22, and a known tread unit 23. A transmission device 24 is provided tocouple the apparatus 3 to each of the pull unit 21, the leg extensionunit 22 and the tread unit 23. The transmission device 24 includes ropemeans 241 coupled to the pull unit 21 and the leg extension unit 22,belt means 242 coupled to the tread unit 23, and a set of pulleys 243for controlling transmission direction of the rope and belt means 241,242.

With further reference to FIGS. 2 and 3, the apparatus 3 of thisembodiment includes a wheel unit 51, a resistance generator 7, anelectrically controlled torque transfer device 8, an angle measuringdevice 52, and a control unit 6.

The wheel unit 51 is coupled to the rope means 241 and the belt means242 of the transmission device 24. The wheel unit 51 is thus operable soas to rotate in response to exertion of a user-applied force on any oneof the pull unit 21, the leg extension unit 22 and the tread unit 23during exercise. In this embodiment, the wheel unit 51 includes a wheelshaft 512 mounted rotatably on the exercise machine 2, and an opticalencoder wheel 510 mounted co-rotatably on the wheel shaft 512 and formedwith a plurality of angularly displaced radial slots 511.

The resistance generator 7 is mounted on the exercise machine 2, andincludes an electric motor 72 that is operable so as to generate aresistive torque for resisting rotation of the wheel unit 51 when theuser-applied force is exerted. A known transmission unit 73, whichincludes two transmission wheels 731, 732 and a transmission belt 733trained on the transmission wheels 731, 732, is used to transmit theresistive torque generated by the motor 72 to the torque transfer device8.

The torque transfer device 8 couples the transmission unit 73 of theresistance generator 7 to the wheel shaft 512 of the wheel unit 51, andis operable so as to transfer a fraction of the resistive torque fromthe resistance generator 7 to the wheel unit 51. In this embodiment, thetorque transfer device 8 includes a conventional electromagneticmechanical particle clutch. Since the feature of the invention does notreside in the specific construction of the known torque transfer device8, details of the same are omitted herein for the sake of brevity.

The angle measuring device 52 is mounted on the exercise machine 2proximate to the wheel unit 51, and serves to detect angular rotation ofthe wheel unit 51 during each exercise stroke when the pull unit 21 orthe leg extension unit 22 is in use. In this embodiment, the anglemeasuring device 52 includes a known photoelectric sensor associatedoperably with the optical encoder wheel 510 of the wheel unit 51.Preferably, the radial slots 511 of the optical encoder wheel 510 areformed at 10-degree intervals.

The control unit 6 is coupled to the torque transfer device 8, the anglemeasuring device 52 and the resistance generator 7, and includes acontrol panel 61 for inputting user settings, a processor 62 connectedto the control panel 61 and the angle measuring device 52, a motordriver 65 connected to the processor 52 and the electric motor 72 of theresistance generator 7 for controlling activation of the electric motor72 and direction of the resistive torque generated by the electric motor72, a digital-to-analog (D/A) converter 63 connected to the processor62, and a current controller 64 connected to the D/A converter 63 andthe torque transfer device 8 for controlling operation of the torquetransfer device 8.

The control panel 61 can be operated to select the type of exercise tobe performed by the user, i.e., which one of the pull unit 21, the legextension unit 22 and the tread unit 23 is intended to be used, and atarget resistive force value for the exercise to be performed by theuser. The control panel 61 can be disposed in front of the pull and legextension units 21, 22, or in front of the tread unit 23 to facilitateuser operation.

Depending on the type of exercise to be performed, the processor 62controls activation of the electric motor 72 of the resistance generator7 through the motor driver 65 such that the resistive torque generatedby the resistance generator 7 can resist rotation of the wheel unit 51due to application of the user-exerted force on the selected one of thepull unit 21, the leg extension unit 22, and the tread unit 23.

The processor 62 has predetermined load variation curves for thedifferent types of exercise stored therein. Since the feature of thepresent invention does not reside in the load variation curves, whichare obtained through known techniques, a detailed description of thesame is omitted herein for the sake of brevity. The processor 62receives the user settings inputted through the control panel 61, andcalculates different resistive load values with reference to the usersettings and the load variation curve for the type of exercise to beperformed by the user. Thereafter, with further reference to the angularrotation of the wheel unit 51 detected by the angle measuring device 52,the processor 62 generates varying torque control outputs thatcorrespond to the calculated resistive load values.

The D/A converter 63 receives the torque control output of the processor62, and converts the same into an analog control signal. The currentcontroller 64 subsequently converts the control signal into a controlcurrent that is supplied to an electromagnet (not shown) of the torquecontrol device 8. In response to the control current, the torque controldevice 8 adjusts the fraction of the resistive torque that istransferred from the resistance generator 7 to the wheel unit 51,thereby resulting in a variable resistive load during exercise.

FIG. 4 is a flowchart to illustrate operation of a preferredimplementation of the control unit 6. In the flowchart of FIG. 4, it isassumed that the leg extension unit 22 was selected by the user, and theuser inputted 30 kilograms as his target resistive force value. Duringan exercise stroke, the user exerts a force to move the leg extensionunit 22 with the use of his legs such that the user's legs are movedfrom an initial position, where the user's legs stand uprightly on theground, toward a fully extended position, i.e., the user's legs aresubstantially horizontal. The angle measuring device 52 detects theangular rotation of the wheel unit 51 during each exercise stroke, andprovides the detected information to the processor 62. The processor 62gradually increases the torque control output thereof with reference tothe predetermined load variation curve for the leg extension unit 22 incase of an increase in angular displacement of the wheel unit 51 from aninitial position, and gradually decreases the torque control output withreference to the same predetermined load variation curve for the legextension unit 22 in case of a decrease in the angular displacement ofthe wheel unit 51 from the initial position. For instance, during aninitial stage of a current exercise stroke, the torque control output ofthe processor 62 can be set to 20% of the target resistive force value.The torque control output is then gradually increased to increase thefraction of the resistive force that is transferred to the wheel unit 51as the angular displacement of the wheel unit 51 from its initialposition increases. When the user's legs are at the fully extendedposition, the torque control output of the processor 62 can be set tocorrespond to 120% of the target resistive force value, i.e., 36kilograms. Thereafter, when the user's legs are moved from the fullyextended position back to the initial position, the processor 62gradually decreases its torque control output from an initial valuecorresponding to 40% of the target resistive force value, i.e., 12kilograms, to a value corresponding to 0% of the target resistive forcevalue (which is the resistive force transferred to the wheel unit 51when the user's legs are at the initial position). Since the resistiveload transferred to the wheel unit 51 varies with the measured angulardisplacement of the wheel unit 51, the risk of injury can be reduced toa minimum during exercise.

Preferably, the processor 62 is configured to control the control panel61 to show the current resistive load transferred to the wheel unit 51thereon for user monitoring purposes.

FIG. 5 is a flowchart to illustrate operation of another preferredimplementation of the control unit 6. In the flowchart of FIG. 5, thefraction of the resistive torque is increased upon detection that thetime for the wheel unit 51 to reach a predetermined angular displacementduring the current exercise stroke is smaller than a first threshold,and is reduced upon detection that the time for the wheel unit 51 toreach the predetermined angular displacement during the current exercisestroke is greater than a second threshold.

In the flowchart of FIG. 5, it is assumed that the leg extension unit 22was selected by the user, and that the standard time period forcompleting a lifting action of an exercise stroke ranges from 1.6 to 2.4seconds. During an initial exercise stroke, the torque control output ofthe processor 62 can be set to correspond to a 20-kilogram resistiveload. If the time that took for the user to move his legs from theinitial position to the fully extended position is smaller than 1.6seconds (the first threshold, t_(min)), this indicates that theresistive load is too small, and the control unit 6 controls the torquetransfer device 8 to increase the resistive torque transferred to thewheel unit 51 to 25 kilograms for the succeeding exercise stroke. On theother hand, if the time that took for the user to move his legs from theinitial position to the fully extended position is greater than 2.4seconds (the second threshold, t_(max)), this indicates that theresistive load is too heavy, and the control unit 6 controls the torquetransfer device 8 to reduce the resistive force transferred to the wheelunit 51 to 15 kilograms for the succeeding exercise stroke. As a result,the resistive load is dynamically varied according to the actualcondition of the user during exercise in order to minimize the risk ofinjury.

Preferably, the processor 62 of the control unit 6 is adapted to becoupled to an external computer 620 to permit downloading of the loadvariation curves for the different types of exercise therefrom.

While the present invention has been described in connection with whatis considered the most practical and preferred embodiment, it isunderstood that this invention is not limited to the disclosedembodiment but is intended to cover various arrangements included withinthe spirit and scope of the broadest interpretation so as to encompassall such modifications and equivalent arrangements.

1. A method for providing a dynamically variable resistive load duringexercise, the method being implemented using an apparatus that includesa wheel unit that is operable so as to rotate in response to exertion ofa user-applied force during an exercise stroke, a resistance generatorthat is operable so as to generate a resistive torque for resistingrotation of the wheel unit when the user-applied force is exerted, andan electrically controlled torque transfer device that couples theresistance generator to the wheel unit and that is operable so as totransfer a fraction of the resistive torque from the resistancegenerator to the wheel unit, the method comprising the steps of: a)detecting angular rotation of the wheel unit during each exercisestroke; and b) in accordance with the detected angular rotation of thewheel unit during a current exercise stroke, controlling the torquetransfer device to adjust the fraction of the resistive torque that istransferred to the wheel unit.
 2. The method as claimed in claim 1,wherein, in step b), the fraction of the resistive torque is graduallyincreased with an increase in angular displacement of the wheel unitfrom an initial position during the current exercise stroke, and isgradually reduced when otherwise.
 3. The method as claimed in claim 1,wherein, in step b), the fraction of the resistive torque is increasedupon detection that the time for the wheel unit to reach a predeterminedangular displacement during the current exercise stroke is smaller thana first threshold, and is reduced upon detection that the time for thewheel unit to reach the predetermined angular displacement during thecurrent exercise stroke is greater than a second threshold.
 4. Anapparatus for providing a dynamically variable resistive load duringexercise, comprising: a wheel unit that is operable so as to rotate inresponse to exertion of a user-applied force during an exercise stroke;a resistance generator that is operable so as to generate a resistivetorque for resisting rotation of said wheel unit when the user-appliedforce is exerted; an electrically controlled torque transfer device thatcouples said resistance generator to said wheel unit and that isoperable so as to transfer a fraction of the resistive torque from saidresistance generator to said wheel unit; an angle measuring device fordetecting angular rotation of said wheel unit during each exercisestroke; and a control unit coupled to said torque transfer device andsaid angle measuring device; wherein, in accordance with the angularrotation of said wheel unit detected by said angle measuring deviceduring a current exercise stroke, said control unit controls said torquetransfer device to adjust the fraction of the resistive torque that istransferred to said wheel unit.
 5. The apparatus as claimed in claim 4,wherein said control unit controls said torque transfer device togradually increase the fraction of the resistive torque with an increasein angular displacement of said wheel unit from an initial positionduring the current exercise stroke, and to gradually reduce the fractionof the resistive torque when otherwise.
 6. The apparatus as claimed inclaim 4, wherein said control unit controls said torque transfer deviceto increase the fraction of the resistive torque upon detection that thetime for said wheel unit to reach a predetermined angular displacementduring the current exercise stroke is smaller than a first threshold,and to reduce the fraction of the resistive torque upon detection thatthe time for said wheel unit to reach the predetermined angulardisplacement during the current exercise stroke is greater than a secondthreshold.
 7. The apparatus as claimed in claim 4, wherein saidresistance generator includes an electric motor that is coupled to saidcontrol unit so as to control activation of said electric motor.
 8. Theapparatus as claimed in claim 7, wherein said control unit is furtheroperable so as to control direction of the resistive torque generated bysaid electric motor.
 9. The apparatus as claimed in claim 4, whereinsaid torque transfer device includes an electromagnetic mechanicalparticle clutch.
 10. The apparatus as claimed in claim 4, wherein saidwheel unit includes an optical encoder wheel, and said angle measuringdevice includes a photoelectric sensor operably associated with saidoptical encoder wheel.